Industry Segment Information (Schedule of Sales and Operating Income by Operating Segment, Excluding Discontinued Operations) (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 29, 2014		Jun. 30, 2013		Jun. 29, 2014		Jun. 30, 2013
Segment Reporting [Abstract]
Defined Benefit Plan, Recognized Net (Gain) Loss on Mark-to-Market	$ 0		$ 0		$ (100,000)		$ (100,000)
Segment Reporting Information [Line Items]
Revenue	556,170,000		540,673,000		1,086,780,000		1,043,616,000
Operating income (loss) from continuing operations	69,637,000		40,216,000		121,399,000		76,910,000
Interest and other expense, net	8,964,000		12,865,000		20,253,000		24,905,000
Income from continuing operations before income taxes	60,673,000		27,351,000		101,146,000		52,005,000
Sales Revenue, Goods, Net	381,609,000		374,024,000		747,093,000		720,643,000
Sales Revenue, Services, Net	174,561,000		166,649,000		339,687,000		322,973,000
Human Health [Member]
Segment Reporting Information [Line Items]
Revenue	307,505,000		297,319,000		605,694,000		576,213,000
Operating income (loss) from continuing operations	52,614,000		30,628,000		96,704,000		56,441,000
Sales Revenue, Goods, Net	245,108,000		235,923,000		484,137,000		454,996,000
Sales Revenue, Services, Net	62,397,000		61,396,000		121,557,000		121,217,000
Environmental Health [Member]
Segment Reporting Information [Line Items]
Revenue	248,665,000		243,354,000		481,086,000		467,403,000
Operating income (loss) from continuing operations	30,872,000		19,298,000		52,371,000		40,026,000
Sales Revenue, Goods, Net	136,501,000		138,101,000		262,956,000		265,647,000
Sales Revenue, Services, Net	112,164,000		105,253,000		218,130,000		201,756,000
Corporate [Member]
Segment Reporting Information [Line Items]
Operating income (loss) from continuing operations	$ (13,849,000)	[1]	$ (9,710,000)	[1]	$ (27,676,000)	[1]	$ (19,557,000)	[1]

[1] Activity related to the mark-to-market adjustment on postretirement benefit plans has been included in the Corporate operating loss from continuing operations, and in the aggregate constituted a pre-tax gain of $0.1 million for both the six months ended June 29, 2014 and June 30, 2013. There were no expenses related to the mark-to-market adjustment on postretirement benefit plans for either the three months ended June 29, 2014 or June 30, 2013.